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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [AVX] partly-implemented 256-bit ISA leads to codegen problems"
href="https://bugs.llvm.org/show_bug.cgi?id=32790">32790</a>
</td>
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<tr>
<th>Summary</th>
<td>[AVX] partly-implemented 256-bit ISA leads to codegen problems
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>All
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Backend: X86
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>spatel+llvm@rotateright.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>define <8 x i32> @legality_problems(<8 x i32> %a, <8 x i32> %b, <8 x i32> %c,
<8 x i32> %d) {
%add = add <8 x i32> %a, %b
%and = and <8 x i32> %add, %c
%sub = sub <8 x i32> %and, %d
ret <8 x i32> %sub
}
We'd be better off sticking to 128-bit ops here:
$ ./llc -o - v256.ll -mattr=avx
vextractf128 $1, %ymm1, %xmm4
vextractf128 $1, %ymm0, %xmm5
vpaddd %xmm4, %xmm5, %xmm4
vpaddd %xmm1, %xmm0, %xmm0
vinsertf128 $1, %xmm4, %ymm0, %ymm0
vandps %ymm2, %ymm0, %ymm0
vextractf128 $1, %ymm0, %xmm1
vextractf128 $1, %ymm3, %xmm2
vpsubd %xmm2, %xmm1, %xmm1
vpsubd %xmm3, %xmm0, %xmm0
vinsertf128 $1, %xmm1, %ymm0, %ymm0
retq</pre>
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</p>
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